Abstract: For the technical plan of reducing SO₂ concentration from 960 mg/m³ to below 500 mg/m³ in Claus unit tail gas, it was pointed out that decreasing lean solution temperature and H₂S concentration in selective absorber of SCOT unit, the total sulfur recovery rate can be effectively increased to more than 99.9%. If formulated solvents are used in addition, the efficiency of selective absorption and total sulfur recovery rate could be further improved. Currently industrial data showed that Cansolv method belongs to oxidation-absorption technology of tail gas treatment and the total sulfur recovery is lower than that of standard-type SCOT units. Therefore, the adoption of Cansolv technology for treating the tail gas of Claus unit should be carefully reviewed.